Tens of thousands of angry protesters have camped in city squares across Egypt, calling for the sacking of the former regime's remnants, including the head of Egypt's Military Council.

Tents set up in Cairo, Alexandria, Suez as well as several smaller cities, remained in place on Sunday.

The demonstrators blocked traffic and formed picket lines outside the government complexes in central Cairo on Sunday.

"We managed to convince many of the employees not to go to work," AFP quoted a human rights activist as saying.

They have launched an open strike in Cairo and other big cities, threatening to escalate their protests unless their demands are met.

The protesters are demanding public trials for ousted president Hosni Mubarak and those behind the killing of hundreds of protesters during the revolution.

They also want Head of Egypt's Military Council Field Marshal Mohamed Hussein Tantawi to resign and hand over power to a civilian government.

On Saturday, Prime Minister Essam Sharaf vowed to suspend all officers accused of killing protesters. He also promised to speed up court cases against them.

The protesters have vowed to keep up their sit-in despite a series of concessions by the Egyptian prime minister.

The activists have slammed the concessions as empty rhetoric with vague promises and no deadlines.

"We are also asking for the release of civilians held by the military, an increase in salaries and we want the ex-regime ministers out," an activist said in Cairo's Liberation Square.

Many are complaining that more and more civilians are being tried in military courts while members of Mubarak's regime have not yet faced justice.

Many of them were protesters detained during anti-government demonstrations in February that toppled Mubarak.

The fresh protests come as Egypt's ruling military junta has freed a number of policemen accused of involvement in the killings. People accuse the judiciary of corruption.

On Friday, Egypt saw mass protests across the country demanding that the former officials be tried quickly and in public.

Following Mubarak's downfall, the military council took over in Egypt. Many Egyptians believe it is trying to derail the uprising.

Egyptians are still skeptical about a rapid transition towards democracy and civilian rule in the North African country.